Many integrated circuits include digital circuits that require a reset operation of some sort before these digital circuits are capable of operating properly. For example, a power-on-reset may be required after a system has been powered “on” or after a system has been woken up from a low-power sleep mode.
Integrated television (TV) tuners that include digital circuits are such integrated circuits that utilize power-on-reset signals to provide for proper operation of the digital circuits. Because of compatibility issues with older analog TV tuners, some TV module manufacturers are unable to provide external reset signals to TV tuner integrated circuits that include digital circuits needing such reset signals. One prior solution to this problem has been to add external power-on-reset (POR) circuitry to a TV module printed circuit board, and this external POR circuitry then provides an external reset signal to a TV tuner integrated circuit mounted on the TV module. However, this additional external POR circuitry increases cost of the TV module.
FIG. 1 (Prior Art) is a block diagram of an embodiment 100 that utilizes external POR circuitry 106 to provide an external reset signal 108 to a integrated circuit (IC) 102, which can be a TV tuner IC if desired. As depicted, the external reset signal 108 is provided to a reset pin 110 for the integrated circuit 102, and this external reset signal 108 is used to provide an internal reset signal 104 for the digital circuitry within the integrated circuit 102. The POR circuitry 106 can be implemented to use standard POR circuitry that monitors the supply voltage 112 and provides the external reset signal 108 when the supply voltage 112 has reached a threshold voltage level that is sufficiently high to provide successful operation of the integrated circuit 102. As stated above, this external POR circuitry 106 adds undesirable cost.